In this study, we have developed, for the first time, a facile in situ growth process to prepare a hierarchical three-dimensional (3D) composite composed of graphene layers with layered double hydroxide (LDH) nanosheet arrays grown on both sides. The fabrication process involves coating AlOOH colloids onto the graphene surfaces and the subsequent in situ growth of layered NiAl–LDH nanosheet arrays on the surfaces of graphene sheets via a hydrothermal process. It is found that the NiAl–LDH nanosheet arrays grow perpendicularly and uniformly on both sides of the graphene sheets, constructing a hierarchical 3D nanocomposite with an interesting sandwich structure. This uniquely structured composite has a large specific surface area (184.7 m² g⁻¹) and typical mesoporous characteristics, which are favorable for achieving high pseudocapacitance performance. Our results reveal that the composite has a specific capacitance of 1329 F g⁻¹ at a current density of 3.57 A g⁻¹, and the specific capacitance still remains as high as 851 F g⁻¹ even when the current density is increased to 17.86 A g⁻¹. The specific capacitance remains at 91% (823 F g⁻¹) after 500 cycles at 15.30 A g⁻¹ compared with 74% for pure Ni/Al–LDH. The in situ growth method may pave a way to design and fabricate diverse LDH/graphene composites with interesting structures for potential application in supercapacitors and other fields.

Chemical C–N coupling from CO₂ and NO₃^–, driven by renewable electricity, toward urea synthesis is an appealing alternative for Bosch–Meiser urea production. However, the unmatched kinetics in CO₂ and NO₃^– reduction reactions and the complexity of C- and N-species involved in the co-reduction render the challenge of C–N coupling, leading to the low urea yield rate and Faradaic efficiency. Here, we report a single-atom copper-alloyed Pd catalyst (Pd₄Cu₁) that can achieve highly efficient C–N coupling toward urea electrosynthesis. The reduction kinetics of CO₂ and NO₃^– is regulated and matched by steering Cu doping level and Pd₄Cu₁/FeNi(OH)₂ interface. Charge-polarized Pd^δ–-Cu^δ+ dual-sites stabilize the key *CO and *NH₂ intermediates to promote C–N coupling. The synthesized Pd₄Cu₁-FeNi(OH)₂ composite catalyst achieves a urea yield rate of 436.9 mmol g_cat.^–1 h^–1 and Faradaic efficiency of 66.4%, as well as a long cycling stability of 1000 h. In-situ spectroscopic results and theoretical calculation reveal that atomically dispersed Cu in Pd lattice promotes the deep reduction of NO₃^– to *NH₂, and the Pd-Cu dual-sites lower the energy barrier of the pivotal C–N coupling between *NH₂ and *CO.

We developed a new strategy, i.e., a seed-assisted method, to fabricate a three-dimensional (3D) SiO₂@Fe₃O₄ core/shell nanorod array/graphene architecture. The fabrication processes involved deposition of β-FeOOH seeds on the graphene surfaces in the ferric nitrate aqueous solution, subsequent growth of β-FeOOH nanorod arrays on the graphene surfaces in the ferric chloride aqueous solution under hydrothermal conditions, deposition of SiO₂ coating on the surfaces of β-FeOOH nanorods, and final formation of the 3D architecture by a thermal treatment process. Scanning electron microscopy and transmission electron microscopy measurements showed that the SiO₂@Fe₃O₄ core/shell nanorods with a length and diameter of about 60 and 25 nm, respectively, were almost grown perpendicularly on both side surfaces of graphene sheets. The measured electromagnetic parameters showed that the 3D architecture exhibited excellent electromagnetic wave absorption properties, i.e., more than 99% of electromagnetic wave energy could be attenuated by the 3D architecture with an addition amount of only 20 wt% in the paraffin matrix. In addition, the growth mechanism of the 3D architecture was proposed, and thus, the strategy presented here could be used as a typical method to synthesize other 3D magnetic graphene nanostructures for extending their application areas.

3D hierarchical MoS ₂ nanoflake array/carbon cloth is synthesized with a thickness of MoS ₂ nanoflakes <15 nm. A full Li battery based on the cloth exhibits good electrochemical performance and high flexibility.